ORIGIN OF SEX. 27 
We have seen, then, that excessive ‘‘ vigor” increases the pro- 
portion of females ; lessened ‘‘ vigor” decreases the proportion of 
males (apparently increases the proportion of females) ; and that 
greater ‘‘ vigor” increases the proportion of males :— from all of 
which we conclude that there is no constant ‘relationship between 
‘vigor’ and sex.” 
In my paper on the “ Relative Viability of the Sexes, etc.,” in 
which I have shown that females have a higher viability (greater 
longevity) than males, I ventured to ascribe this greater viability 
to the fact of female fetuses sapping the vitality of the mother 
more than males. However this be, there can be no doubt of the 
facts stated, for Prof. Martegoute* in his observations on the 
breeding of the Dishley Mauchamp merino sheep, says,—‘‘ Our 
monthly weighings show that the ewes that have produced female 
lambs are on an ayerage of weight superior to those that 
produced the males; and they evidently lose more in weight than 
these last, during the suckling period; while the ewes that pro- 
duce males, weigh less, and do not lose in nursing so much as 
the others.”7 ‘That is, mothers are in better condition when they 
conceive females, and are in better condition when they wean 
males than females.” Dr. Congar{ has observed the same thing 
concerning women. Dr. Spruce,§ a South American traveller, 
noticed that a certain palm (Geonoma) bore fruit (female flowers) 
one year, and male flowers the next, alternating from male to 
female from year to year. This same fact is seen in some ani- 
mals, that bear females for several generations, then males; in 
fact the process of ‘alternation of generations” is dependent 
upon this principle, of which I shall have more to say in another 
paper. || 
I have stated that some stalks bore only male flowers, and sug- 
gested that this fact was the result of retarded fecundation of the 
ovule from which the stalk was produced, and I may now point 
out how nature allows these peculiarities to be produced. 
It has been observed, says Lindley, that the quantity and kind 
of light to which the plant is subjected determine the sex of the 
* Journal d'Agriculture Pratique, ete 
t Goodale, Breeding, etc. of Domestic Animals. Boston, 1861, pp. 91, 92. 
İH. M. Congar, M. D., Buffalo Medical and Surgical Journal, August, 1867. 
§ Criticism on Dr. Spruce’s article, by Dr. Wendland, in Botan. Zeitung, 1869. 
The Cause of Rotation and ep E Number of Sexes in Births. 
ry of Horticulture, N. 
